Cover device for a power tool

ABSTRACT

A cover device for partially covering a front, in an axial direction, side of a disc-shaped working tool ( 10 ) of a power tool includes a bearing element ( 22 ) securable on the shielding member ( 12 ), which partially radially covers the working tool ( 10 ), and having a bearing surface ( 28 ) abutting, at least regionwise, an outer surface ( 14 ) of the shielding member ( 12 ), a protective disc ( 30 ) extending substantially transverse to the bearing surface ( 28 ) of the bearing means ( 22 ), and engaging-from-behind elements ( 24 ) provided at opposite tangential ends of the bearing surface ( 28 ), respectively, with at least one of the engaging-from-behind elements ( 24 ) being elastically pivotal in a radial direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a cover device for partially covering afront, in an axial direction, side of a disc-shaped grinding orseparating tool of a power tool, in particular, of an angle grinder. Thecover device is designed in particular to be retrofitted on the powertool. The cover device is provided with a bearing member having abearing surface securable, when required, over a shielding member thatpartially covers the working tool. The bearing surface at leastregionwise abuts the outer surface of the strip-shaped shielding member.The cover device also includes a protective disc which extendssubstantially transverse to the bearing surface and which partiallycovers the front, in the axial direction, side of the working tool.

2. Description of the Prior Art

Most of angle grinders are equipped, standardwise, with a shieldingmember which is formed as a protective plate having an acruatecross-section in the longitudinal direction and which is secured to atruncated cone section provided on the power tool head of the powertool. The shielding member partially covers the working tool in theradial direction. With the power tool having such shielding member, thepower tool can be retrofitted, if needed, in such a way that the workingtool front side would be partially covered in the axial direction. Withthe tool being partially covered in the axial direction, the userbecomes effectively protected from accelerating material particles, inparticular sparks, also in the axial direction. On the other hand, withthe protective disc extending substantially transverse to the bearingsection, the cover means forms a space around the working tool a majorpart of which is closed. The closed space insures an effective suctionof removable material particles.

The language “substantially transverse,” which is used above, means thatthe protective disc is arranged somewhat transverse to the overalldirection of the bearing surface independent from the shape of thebearing surface of the bearing means.

German document 94 03 777 discloses a cover device for an angle grinderand which has a protective disc on which an additional cover ispivotally supported. The disc has a jacket element that partiallyextends over its circumference and that surrounds the shielding member.The cover device is forcelockingly secured on the angle grinder.

The known cover device covers the working tool well during operation.However, the manufacturing costs of the device of DE 94 03 777 arerelatively high. In addition, the means that provides for theforcelocking connection of the cover device on the power tool, such as,e.g., clamp screws, are either tedious to operate or are not capable toabsorb forces acting on the cover device during the power tooloperation, such as, e.g., tangentially acting impacts, without the coverdevice being displaced.

An object of the present invention is to provide a cover device in whichthe drawbacks of the known tool are eliminated.

Another object of the present invention is to provide a cover devicethat can be produced with reduced manufacturing costs.

A further object of the present invention is to provide a cover devicethat can be rapidly mounted on or dismounted from the power tool.

Yet a further object of the present invention is to provide a coverdevice that would be reliably held on the power tool during operation.

SUMMARY OF THE INVENTION

These and other objects of the present invention, which will becomeapparent hereinafter, are achieved by providing engaging-from-behindelements at opposite tangential ends of the bearing surface,respectively, with at least one of the engaging-from-behind elementsbeing elastically pivotal, i.e., being pivotal with a recoverabledeformation in a radial direction for changing a distance a between theengaging-from-behind elements.

The engaging-from-behind elements provide for a particularly easylocking of the cover device with matching locking means, with thedistance between the engaging-from-behind elements being increased byapplication of corresponding external forces. When the cover device ismounted on the power tool, it can easily be pinned on the shieldingmember, with the distance between the engaging-from-behind elementsassuming its initial value upon removal of external forces as a resultof action of restoring forces which return the at least oneengaging-from-behind element to its initial position. Upon the distancebetween the engaging-from-behind element returning to its initial value,they become locked with the matching locking means of the power tool.Upon release of the cover device, the engaging-from-behind elements aredisplaced away from each other against the restoring force in order tobreak the locking between the engaging-from-behind elements and thematching locking means.

According to a particular advantageous embodiment of the presentinvention, the engaging-from-behind elements extend radially inward fromtangential limiting edges of the bearing surface of the bearing means.Thereby, formation of specific matching means, e.g., in form of groovesor bores, on the shielding member can be avoided, which minimizesmanufacturing costs. In addition, the cover device can be easily andrapidly pinned on the power tool, with the engaging-from-behind elementsengaging from behind the limiting edges of the shielding member,securing the cover device in both tangentional directions.

Advantageously, the at least on of the engaging-from-behind elements isformed as a hook-shaped element securely connected with the bearingmeans. In addition, the protective disc is provided with a substantiallyradially extending slot. The slot gives the cover device a certainelasticity, providing for displacement of the engaging-from-behindelements away from each other under action of external forces, with theelements being returned to their initial position under the action ofrestoring forces. This makes possible an easy mounting of the coverdevice on the power tool and dismounting it therefrom without use of anyassembly or other tools.

Alternatively, the at least one engaging-from-behind element can beformed on a spring-biased locking element. With the locking element, thecover device can be particularly reliably secured on the power tool.

Advantageously, the locking element has a spring arm, with a lockingnose being formed on a free end of the arm and extending radiallyinwardly. The spring arm insures that the locking element automaticallyengages from behind a respective limiting edge upon mounting of thecover device on the power tool. Thereby, a particularly easy connectionof the cover device with the power tool is insured.

Advantageously, the spring arm is formed by two, extending parallel toeach other, cut-ins provided at a tangential end of the bearing surface.This insures a particularly cost-effective manufacturing of the lockingelement.

Advantageously, the engaging-from-behind elements are formed integrallywith the remaining part of the cover device as a one-piece part, i.e.,by deformation or partial removal of the material that forms the coverdevice. Thereby, manufacturing costs are reduced, and a stable lockingelement is produced.

Advantageously, the protective disc extends at least over a half-circledefined by the bearing means. Thereby, the working tool can be coveredparticularly well in order to protect the user from flying sparks andsimilar released and accelerated particles. Easy mounting anddismounting of the cover device also insure a rapid replacement of theworking tool.

The novel features of the present invention, which are considered ascharacteristic for the invention, are set forth in the appended claims.The invention itself, however, both as to its construction and its modeof operation, together with additional advantages and objects thereof,will be best understood from the following detailed description ofpreferred embodiments, when read with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings show:

FIG. 1 a perspective exploded view of a power tool with a cover deviceaccording to the present invention;

FIG. 2 a perspective view of a cover device shown in FIG. 1;

FIG. 3 a a side view of the cover device shown in FIG. 2;

FIG. 3 b a cross-sectional view along line IIIb-IIIb in FIG. 3 a;

FIG. 3 c a detail IIIc in FIG. 3 b at an increased, in comparison withFIG. 3 b, scale;

FIG. 4 a a side view of another embodiment of a cover device;

FIG. 4 b a cross-sectional view along line IVb-IVb in FIG. 4 a; and

FIG. 3 c a detail IVc in FIG. 4 b at an increased, in comparison withFIG. 4 b, scale.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a power tool 2 which is formed as an angle grinder and hasa housing 4 with a tool head 6. The tool head 6 has a tool spindle 8rotatable about an axis A and on which a disc-shaped working tool 10 issecured. Further, there is provided on the tool head 6 a shieldingmember 12 in form of a protective plate that partially surrounds theworking tool 10 in a radial direction. The shielding member 12 has anouter surface 14 having an arcuate cross-section in its longitudinaldirection and a straight section in its transverse direction and theedges of which are rounded.

The working tool 10 is secured on the tool spindle 8 with a toolretaining member 16. For mounting or dismounting the working tool 10 onor from the tool spindle 8, the tool retaining member 16 is tightened orreleased, respectively, using an assembly tool 18 in form of, e.g., awrench or, as shown in FIG. 1, in form of a special tool.

FIG. 1 further shows a cover device 20 according to the presentinvention in a position in which it is taken off the power tool 2. Thecover device 20 can be mounted on the shielding member 12 or dismountedtherefrom without using any assembly tools. To this end, the coverdevice 20 is provided with a strip-shaped bearing means 22 the shape ofwhich substantially corresponds to the profile of the outer surface 14of the shielding member 12.

The cover device 20 further includes inwardly projecting,engaging-from-behind elements 24 which are provided, respectively, atopposite tangential ends of the bearing means 22 and which are spacedfrom each other by a distance a. Upon mounting of the cover device 20 onthe power tool 2, the bearing means 22 abuts the outer surface 14 of theshielding member 12, and the engaging-from-behind elements 24 contactthe outer surface 14 that pushes the elements 24 away from each other.With the elements 24 being pushed away from each other, the distance atherebetween increases. The outer surface 14 is limited in thetangential direction at its opposite ends by limiting edges 26 which aresnapped behind by the engaging-from-behind elements 24 due to therecovery forces generated upon displacement of the elements 24 away fromeach other.

As it is particularly shown in FIG. 2, the cover device 20 has, in adirection perpendicular to a section of a bearing surface 28 of thebearing means 22 which has a straight cross-section, a protective disc30. The protective disc 30 extends over a semicircle defined by thebearing means 20 and covers, in the mounted condition of the coverdevice 20 on the shielding member 12, in the axial direction, thefrontal side of the working tool 10 toward outside, with the protectivedisc 30 projecting in the axial direction partially beyond the toolspindle 8.

FIGS. 3 a-3 c shows a first embodiment of the engaging-from-behindelements 24. The elements 24 have, at their respective free ends, twohook-shaped elements 32 which are formed at the tangential ends of thebearing means 22. The hook-shaped elements 32, together with theengaging-from-behind elements 24, are formed, together with the bearingmeans 22, as a substantially formstable single piece. In order to beable to displace the engaging-from-behind elements 24 away from eachother to increase the distance a therebetween for hooking the coverdevice 20 on the limiting edges 26 of the shielding member 12 and forremoving the cover device 20 off the shielding member 12, there isformed, in the protective disc 30, a radial slot 34. The slot 34 permitsto deform, the bearing means 22 during mounting of the cover device 20on the shielding member 12 and dismounting of the cover device 20 fromthe shielding member 12. The slot 34 provides for a radial pivotalmovement of the engaging-from-behind elements 24, which increases thedistance a therebetween. By radially pivoting the engaging-from-behindelements 24, it is possible to move them past the limiting edges 26 inorder to hook the elements on the limiting edges 26 or to release theelements 24 from the limiting edges 26.

On the inner side of the hook-shaped elements 32, there is formed atrough 36, as particularly shown in FIG. 3 c, which provides for abetter holding of the hook-shaped elements 32 on respective limitingedges 26 of the shielding member 12.

FIGS. 4 a-4 c show an alternative, second embodiment of theengaging-from-behind elements 24. According to this embodiment, theengaging-from-behind elements 24 are formed on a locking nose 38 of anelastically resilient locking element 40. The locking element 40 has aspring arm 42 that is formed by two tangentional, extending parallel toeach other, cut-ins 44 provided at respective tangential ends of thebearing means 22. The cut-ins 44 provide for elastic pivotal movement ofthe engaging-from-behind elements 24 in the radial direction relative tothe bearing means 22 in order to change the distance a therebetween.

With both embodiments of the engaging-from-behind elements 24, the coverdevice 20 can be rapidly pinned on the shielding member 12, withoutusing any additional tools.

In both embodiments, the engaging-from-behind elements 24 engage thelimiting edges 26 in order to secure the cover device 20 on theshielding member 12 in the tangential and radial direction.

Simultaneously, the cover device 20 is secured in the axial directionwith the partially arched bearing surface 28 the profile of whichcorresponds to that of the outer surface 14 and which substantiallyabuts the outer surface 14.

According to a further embodiment of the cover device 20, only oneengaging-from-behind element 24 is provided on the locking element,whereas the other engaging-from-behind element is connected with thebearing member 22 in a formstable manner. In this case, upon mounting ofthe cover device 20, the engaging-from-behind, form-stable element 24should be hooked about a respective limiting edge 26, and the coverdevice 20 should be pivoted about this edge in order to have the other,elastic engaging-from-behind element 24 snap from behind the otherlimiting edge 26.

In the mounted condition of the cover device 20, the protective disc 30would cover the frontal side of the working tool 10 in the axialdirection in order to protect the user better from sparks which aregenerated during the operation of the power tool and similaraccelerating material particles.

In case the working tool 10 need be replaced, the cover device can berapidly removed, without using any tools, by lightly disengaging theengaging-from-behind elements 24 from the shielding member 12 in orderto be able to engage the tool-retaining element with the assembly tool18.

Though the present invention was shown and described with references tothe preferred embodiments, such are merely illustrative of the presentinvention and are not to be construed as a limitation thereof andvarious modifications of the present invention will be apparent to thoseskilled in the art. It is therefore not intended that the presentinvention be limited to the disclosed embodiments or details thereof,and the present invention includes all variations and/or alternativeembodiments within the spirit and scope of the present invention asdefined by the appended claims.

1. A cover device for partially covering a front, in an axial direction,side of a disc-shaped working tool (10) of a power tool having ashielding member (12) that partially radially covers the working tool(10), the cover device comprising: bearing means (22) securable on theshielding member (12) and having a bearing surface (28) abutting, atleast regionwise, an outer surface (14) of the shielding member (12); aprotective disc (30) extending substantially transverse to the bearingsurface (28) of the bearing means (22); and engaging-from-behindelements (24) provided at opposite tangential ends of the bearingsurface (28), respectively, at least one of the engaging-from-behindelements (24) being elastically pivotal in a radial direction forchanging a distance (a) between the engaging-from-behind elements (24).2. A cover device according to claim 1, wherein the engaging-from-behindelements (24) extend radially inward for engaging from behind tangentiallimiting edges (26) of the bearing surface (28) of the bearing means(22).
 3. A cover device according to claim 1, wherein at least one ofthe engaging-from-behind elements (24) is formed as a form-stablehook-shaped element (32) connected with the bearing means (22), andwherein the protective disc (30) is provided with a slot (34).
 4. Acover device according to claim 1, further comprising an elasticallyresilient locking element (40), and wherein at least one of theengaging-from-behind elements (24) is provided on the locking element(40).
 5. A cover device according to claim 4, wherein the lockingelement (40) has a spring arm (42) and a locking nose (38) provided on afree end of the spring arm (42) and extending radially inward.
 6. Acover device according to claim 5, wherein the spring arm (42) is formedby two, extending parallel to each other, cut-ins (44) provided on atangential end of the bearing surface (28).
 7. A cover device accordingto claim 1, wherein the cover device (20), together with theengaging-from-behind elements (24), is formed as a one-piece part.
 8. Acover device according to claim 1, wherein the protective disc (30)extends at least over a half-circle defined by the bearing means (22).